package j20251109;

public class Solution1 {
    int m,n;
    int[] dx={0,0,1,-1};
    int[] dy={1,-1,0,0};
    public void solve(char[][] board) {
        m=board.length;
        n=board[0].length;
        for(int j=0;j<n;j++){
            if(board[0][j]=='O'){
                dfs(board,0,j);
            }
            if(board[m-1][j]=='O'){
                dfs(board,m-1,j);
            }
        }
        for(int i=1;i<m-1;i++){
            if(board[i][0]=='O'){
                dfs(board,i,0);
            }
            if(board[i][n-1]=='O'){
                dfs(board,i,n-1);
            }
        }
        for(int i=0;i<m;i++){
            for(int j=0;j<n;j++){
                if(board[i][j]=='.'){
                    board[i][j]='O';
                }else if(board[i][j]=='O'){
                    board[i][j]='X';
                }
            }
        }
    }
    public void dfs(char[][] board,int i,int j){
        board[i][j]='.';
        for(int k=0;k<4;k++){
            int x=i+dx[k];
            int y=j+dy[k];
            if(x>=0&&x<m&&y>=0&&y<n&&board[x][y]=='O'){
                dfs(board,x,y);
            }
        }
    }
}
